PROJECT SUMMARY Cortical cholinergic signaling is implicated in diverse functions, including arousal and vigilance, signaling of reinforcements, and learning and memory. There is also evidence suggesting cholinergic contributions to value-based decisions. However, decision-making is an elaborate process, influenced by parameters such as value functions, learning rates, reward prediction errors, and so on. Still poorly understood is the extent to which cholinergic signaling may report or regulate specific decision-related parameters. In preliminary studies, we developed a novel adaptation of a value-based decision-making task for head-fixed mice. Analysis and reinforcement learning model fit of the task performance indicate behavior consistent with value-based decisions. In this proposal, we will determine the neural encoding in cortical cholinergic axons by measuring their activity dynamics in the rodent premotor cortex during decision-making (Aim 1). We will determine the influence of fast cholinergic signaling on value-based decisions by manipulating acetylcholine release in the neocortex (Aim 2). Because neuromodulators such as acetylcholine have considerable influence on multiple facets of decision-making, the proposed studies to delineate its computational function will provide insights into the neural basis of value-based decisions.